The apparent and true amino acid (AA) digestibility from soya-bean mea
l (SBM), vetch meal (VM), field pea meal (FPM) and bitter vetch meal (
BVM) were determined in the lower ileum of growing chickens force-fed
on semisynthetic diets (120 g crude protein and 13.1 MJ metabolizable
energy per kg dry matter) based on each meal as the sole source of pro
tein. The average apparent and true digestibility values were 0.82, 0.
73, 0.76 and 0.60 and 0.90, 0.91, 0.87 and 0.74 for diets SBM, VM, FPM
and BVM, respectively. Marked differences in AA digestibility among d
iets were found. The apparent digestibility of methionine, the most li
miting essential AA in poultry diets, was significantly higher in diet
SBM than in diets FPM and BVM (P < 0.05). It is concluded that the se
eds of vetch and field pea may be suitable for inclusion in poultry di
ets as partial substitutes for soya bean. The use of bitter vetch is n
ot recommended.